Chronic kidney disease is linked to systemic inflammation and to an increased risk of ischemic heart disease and atherosclerosis. Endothelial dysfunction associates with hypertension and vascular disease in the presence of chronic kidney disease but the mechanisms that regulate the activation of the endothelium at the early stages of the disease, before systemic inflammation is established remain obscure. In the present study we investigated the effect of serum derived from patients with chronic kidney disease either before or after hemodialysis on the activation of human endothelial cells in vitro, as an attempt to define the overall effect of uremic toxins at the early stages of endothelial dysfunction. Our results argue that uremic toxins alter the biological actions of endothelial cells and the remodelling of the extracellular matrix before signs of systemic inflammatory responses are observed. This study further elucidates the early events of endothelial dysfunction during toxic uremia conditions allowing more complete understanding of the molecular events as well as their sequence during progressive renal failure.

5‐azacytidine (5‐AZA) is considered the standard of care for patients with high‐risk myelodysplastic syndromes (MDS) and patients with acute myeloid leukemia (AML) not candidate for intensive chemotherapy. However, even after an initial favorable response, almost all patients relapse, with the exact mechanisms underlying primary or secondary 5‐AZA resistance remaining largely unknown. Several reports have previously demonstrated the significance of hypoxia in the regulation of both physiological and malignant hematopoiesis. In MDS, high hypoxia inducible factor 1α (Hif‐1α) expression has been correlated with poor overall survival and disease progression, while its involvement in the disease's pathogenesis was recently reported. We herein investigated the possible association of the Hif‐1α signaling pathway with response to 5‐AZA therapy in MDS/AML patients. Our data demonstrated that 5‐AZA‐responders present with higher Hif‐1α mRNA and protein expression compared to 5‐AZA‐non‐responders/stable disease patients, before the initiation of therapy, while, interestingly, no significant differences in Hif‐1α mRNA expression at the 6‐month follow‐up were observed. Moreover, we found that 5‐AZA‐responders exhibited elevated mRNA levels of the Hif‐1α downstream targets lactate dehydrogenase a (LDHa) and BCL2 interacting protein 3 like (BNIP3L), a further indication of an overactivated Hif‐1a signaling pathway in these patients. Kaplan–Meier survival analysis revealed a significant correlation between high Hif‐1α mRNA expression and better survival rates, while logistic regression analysis showed that Hif‐1α mRNA expression is an independent predictor of response to 5‐AZA therapy. From the clinical point of view, apart from proposing Hif‐1α mRNA expression as a significant predictive factor for response to 5‐AZA, our data offer new perspectives on MDS combinational therapies, suggesting a potential synergistic activity of 5‐AZA and Hif‐1α inducers, such as propyl hydroxylases inhibitors (PHDi).

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Background: The currently used prognostic systems for myelodysplastic syndromes (MDS) do not consider the prognostic role of monocytopenia, although monocytes may participate in the prognosis of the disease as part of the host immunity. Aim: We studied the prognostic significance of monocytopenia in patients with MDS registered in the Hellenic National MDS registry. Methods: We analyzed clinicopathological data from patients with MDS recorded in a large retrospective national registry. Patients with MDS/MPN were excluded, while patients treated with allogeneic hematopoietic cell transplantation were censored for overall survival (OS) and leukemia-free survival (LFS). IBM SPSS statistics, version 23.0 (IBM Corporation, North Castle, NY, USA) was used for the analysis of the results. Kaplan-Meier survival analysis and Cox regression analysis were performed for LFS and OS. Results: The study comprised 1719 patients with MDS per the 2008 WHO classification for MDS. The main characteristics of the patients are shown in Table 1. At the time of data cut-off, 818 patients were deceased and the median follow-up for the remaining 901 patients was 23.0 months. The median absolute monocyte count (AMC) was 0.30 x 109/L (0.00 - 0.99 x 109/L). Patients with excess blasts (RAEB1/2) tended to have lower AMCs (median 0.19 versus 0.32 for patients without excess blasts, p<0.0001) and lower AMCs were found in higher IPSS-R categories (very low, 0.37 x 109/L; low, 0.30 x 109/L; intermediate, 0.25 x 109/L; high, 0.16 x 109/L; very high, 0.20 x 109/L) while there was a highly significant difference between lower risk (very low and low) and higher risk (intermediate, high, very high) MDS (0.33 x 109/L vs 0.21 x 109/L, p<0.0001). In univariate analysis, patients with AMCs below 0.2 x 109/L had a median OS of 34.0 months vs 63.0 months for patients with higher AMCs (p<0.0001) with a hazard ratio (HR) for death of 1.57 (95% CI 1.37 - 1.81, p<0.0001). In a multivariate Cox regression model including hemoglobin below 10 g/dL, absolute neutrophil count (ANC) below 1.0 x 109/L, and platelet count below 100 x 109/L (all of them being prognostic for OS in univariate analysis), monocytopenia retained its prognostic significance (HR, 1.16; 95% CI, 1.00 - 1.36, p=0.049). There was a positive correlation between the AMC and the ANC (Pearson Correlation 0.393, p<0.0001). Nevertheless, in a model comprising of AMC and ANC, both variables were independently correlated to OS. Moreover, in a model including AMC below 0.2 x 109/L, the cytogenetic risk score per the IPSS-R, the number of cytopenias, and bone marrow blasts (categorized per the IPSS-R), no additional prognostic impact was found for AMC (HR, 1.01; 95% CI, 0.86 - 1.17; p=0.957). After stratification per the IPSS-R categories, low AMC was prognostic for low OS only in patients with low IPSS-R (median OS, 57 months for patients with low AMC vs 75 months for those with high AMC, p=0.039), but there was no additional prognostic impact after multivariate analysis. Moreover, AMC was prognostic for LFS, since patients with low AMCs (<0.2 x109/L) had a median LFS of 57.0 months, while the median LFS for patients with higher AMCs was not reached (HR, 2.47, 95% CI, 2.01 - 2.47, p<0.0001). In a Cox regression model including the above stated factors (cytopenias, bone marrow blasts, cytogenetic risk, and AMC), AMC retained its prognostic significance for LFS (HR, 1.27; 95% CI, 1.02 - 1.58; p=0.031). In a subgroup of 162 patients treated with hypomethylating agents (HMAs), monocytopenia was not predictive or response to treatment, but low AMC was correlated to a shorter median progression free survival (27.0 months vs not reached for patients with higher AMC, p=0.001). This correlation was not translated into a survival benefit (survival after HMA initiation, 27.0 vs 28.0 months respectively, log rank p=0.213). Conclusions: Based on a large patient cohort, we found that patients with MDS with excess blasts as well as higher risk patients per the IPSS-R have low AMCs. Moreover, we showed that low AMCs are prognostic of lower OS in univariate analysis and of lower LFS in both univariate and multivariate analysis, highlighting a possible pathogenetic role for AMCs in MDS. Further analysis is needed to define the exact prognostic role of AMC in MDS. Disclosures Pappa: Amgen: Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene / GenesisPharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Honoraria, Research Funding; Abbvie: Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Kotsianidis:Celgene: Research Funding. Symeonidis:MSD: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Research Funding; Tekeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding. Vassilakopoulos:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; WinMedica: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene / GenesisPharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees.

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Introduction - Aims: Several prognostic scoring systems have been developed for patients with myelodysplastic syndromes (MDS), including the International Prognostic System (IPSS), the WHO Prognostic Scoring System (WPSS) and the Revised IPSS (IPSS-R). We evaluated the prognostic value of the IPSS-R on an independent group of 2,582 Greek patients with MDS, registered in the Hellenic National MDS Registry. The aim of this multicenter study was to validate the IPSS-R as a predictor for leukemia-free survival (LFS) and overall survival (OS), in newly-diagnosed MDS patients and to compare its prognostic significance with that of IPSS and WPSS. Moreover, to investigate the predictive value of IPSS-R in association with other recognized prognostic variables, such as patient's age, baseline serum lactate dehydrogenase (LDH), and ferritin concentrations, IPSS, WPSS, Eastern Cooperative Oncology Group (ECOG) performance status, transfusion dependency, and response to first-line treatment. Methods: Clinicopathological data from 2,582 MDS patients, diagnosed between 1/2000 - 1/2015 and registered in the Hellenic National MDS Registry were analyzed. Patients with MDS/MPN were excluded. Data included age, gender, date of diagnosis, clinical characteristics, WHO-2008 classification, laboratory parameters, transfusion dependency, bone marrow aspirate and biopsy morphology, cytogenetic findings, and type of treatment. LFS was calculated from the date of initial diagnosis of MDS until bone marrow blast increased to ≥20% [transformation to acute myeloid leukemia (AML), according to the WHO classification], or last contact. OS was defined as the time from MDS diagnosis to death, or last contact. Patients alive and not having developed AML until last follow-up were censored for OS and LFS, respectively. Kaplan-Meier survival analysis and Cox regression analysis were performed with regard to LFS and OS. Differences between Kaplan-Meier curves were evaluated using the Mantel-Cox (log-rank) test. All significant variables identified by univariate Cox regression analysis and clinical factors important for MDS were used to build the multivariate Cox regression models. Multivariate Cox regression analysis included only those patients for whom the status of all variables was known, and comprised age, serum LDH, and ferritin levels, transfusion dependency, response to first-line treatment, IPSS, WPSS, and IPSS-R. Confidence intervals (CI) were estimated at the 95% level; all tests were two-sided, accepting p<0.05 as indicative of a statistically significant difference. All statistical analyses were performed with the statistical software SPSS (version 21). Results: 1,623 male (62.9%) and 959 female MDS patients with a median age of 74 years at diagnosis were included in the current study. Complete follow-up information was available for 2,376 patients. The estimated median OS was 58 months (95% CI = 52.9 - 63.1 months). For 1,974 patients, data used in the calculation of all three scoring systems were complete, thus allowing risk score calculation and comparison of the three risk assessment systems. Median OS was significantly different in patient subgroups classified according to IPSS, WPSS, and IPSS-R, as shown by the Kaplan-Meier survival analysis (p<0.001). Fig. 1 shows Kaplan-Meier OS curves of MDS patients stratified according to IPSS-R (p<0.001). Moreover, the comparison of the prognostic value of the IPSS, WPSS, and IPSS-R revealed that the IPSS-R was significantly superior to both, WPSS and IPSS (p<0.001 in all cases). Multivariate Cox regression analysis demonstrated that the high prognostic value of IPSS-R, in terms of LFS and OS, was independent of patient's age, serum LDH, and ferritin concentration, ECOG performance status, and transfusion dependency (p<0.001). Interestingly, besides IPSS-R, patient age and transfusion dependency retain their small - yet significant - prognostic impact in the multiparametric models, thus implying that these two parameters could add prognostic value to the IPSS-R. Conclusions: Our data support the notion that all three prognostic scores are very useful predictors for both, LFS and OS in MDS, yet IPSS-R is superior to IPSS and WPSS as a prognostic tool, with regard to OS. Disclosures No relevant conflicts of interest to declare.

Introduction: Azacitidine (AZA) is a hypomethylating agent that at low doses acts by inhibiting DNA methyltranferase activity. AZA is approved and widely used for the treatment of MDS patients and patients with AML not candidate for intensive chemotherapy. Unfortunately, even after an initial response, almost all patients relapse and so far -with the exception of a few clinical parameters and genetic mutations weakly correlated with favorable AZA response- the exact mechanisms underlying primary AZA resistance remain largely unknown. On the other hand, over the last years accumulated data suggest that hypoxia, an important regulatory factor of both, physiological and malignant, hematopoiesis, is also involved in MDS pathogenesis (Hayashi et al., 2018), while high Hif-1α levels in MDS have been previously correlated with poor overall survival and disease progression (Tong et al., 2012). Moreover, our group recently investigated the association between Hif-1α and response to AZA therapy and found that AZA-responders present with higher Hif-1α mRNA expression compared to non-responders/stable disease patients, while logistic regression analysis showed that Hif-1α mRNA expression is an independent predictor of response to AZA therapy (unpublished data). Aims: The current study focused on investigating the mechanisms underlying the observed association of Hif-1α over-expression with response to AZA-therapy, by examining the methyltransferase activity and mitochondrial dysfunction due to inactivation of complex II, which is reported to lead to increased Hif-1α expression. Methods: A total of 54 patients with a median age of 76 (52-89) years, and 10, age matched, healthy donors participated in the study. According to WHO 2016, 41 patients were classified as MDS (10 as MDS-EB-1, 24 as MDS-EB-2 and 7 as MDS-MLD) and 13 as AML. All patients received AZA treatment at the dose of 75mg/m2 x7 days SC. BM-derived mononuclear cells were isolated before treatment using the Ficoll-paque method, followed by RNA extraction using TRIzol reagent, and cDNA preparation using Superscript II reverse transcriptase. Hypoxia-inducible factor 1-alpha (Hif-1α), succinate dehydrogenase complex subunit D (DSHd) and DNA methyltrasferase beta (DNMT3b) expression were estimated by real time PCR TaqMan gene expression assays, using the appropriate primers and probes. Relative gene expression was calculated by comparative threshold cycle (2-ΔΔCt) method and normalized based on β-actin expression. Non-parametric tests were used for the statistical analysis of the results. Results: Out of the 54 examined patients, 28 responded to azacitidine treatment (R), (including CR, PR and HI), 9 failed to respond (NR), and 17 achieved stable disease status 9 (SD). NR and SD patients were considered as one group (NR/SD) in all analyses. Using Rt-PCR we found that the 2-ΔΔCt ratio of Hif-1α/β-Actin median expression for control samples was 1.18 (95% CI: 0.617-1.687), for AZA-responders 1.59 (95% CI: 1.029-3.18), while for NR/SD patients 0.754 (95% CI: 0.640-0.840), with a statistical significance between R and NR/SD patients (Mann-Whitney test, p=0.003). Moreover, the 2-ΔΔCt ratio of SDHd/β-Actin median expression for control samples was 1.2 (95% CI: 0.360-1.954), for R patients 0.81 (95% CI: 0.294-1.401), and for NR/SD patients 0.73 (95% CI: 0.542-0.793). Finally, for DNMT3b, the 2-ΔΔCt median expression ratio in control samples was 0.75 (95% CI: 0.637-1.526), for R patients 2.188 (95% CI: 1.547-3.630), while for NR/SD patients 1.338 (95% CI: 0.824-2.250). Conclusions: Our data suggest that both AZA-R and NR/SD patients present with low levels of SDHd mRNA, compared to control, in line with previous reports in MDS. For AZA-responders, this could be related to the observed Hif-1α mRNA over-expression, since the SDH inactivation (decreased Complex II activity) is known to cause HIF stabilization (Frezza et al., 2011; Selak et al., 2005). Nevertheless, NR/SD patients also appear with decreased SDHd activity, despite the observed low Hif-1α expression. Therefore, in those patients, Hif-1α- related AZA-therapy response seems to be independent from mitochondrial dysfunction and possibly relies on other hypoxia regulatory mechanisms. Moreover, our data suggest that AZA-responders appear with an increased DNMT3b expression compared to both control and NR/SD patients, which could also explain their better response to therapy. Disclosures Symeonidis: Pfizer: Research Funding; Sanofi: Research Funding; Tekeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; MSD: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Pappa:Novartis: Honoraria, Research Funding, Speakers Bureau; Celgene / GenesisPharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Honoraria, Research Funding; Amgen: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.